Cryogenic apparatus



Feb. 14, 1967 w. E. PERKINS CRYOGENIC APPARATUS 2 Sheets-Sheet 1 Original Filed April 26, 1956 INVENTOR. WARREN E. PERKINS ATTORNE Feb. 14, 1967 w. E. PERKINS 3,303,667

CRYOGENIC APPARATUS Original Filed April 26, 1956 2 heets-Sheet 2 I I I I I g I l I I l I I I I I I I I I l I A INVENTOR. 1' i WARREN E. PERKINS} 1 BY s2 A TTORNEV United States Patent O 3,303,667 CRYOGENIC APPARATUS Warren E. Perkins, Deerfield, Ill., assignor to Union Carbide Corporation, a corporation of New York Continuation of application Ser. No. 170,354, Feb. 1,

1962, which is a division of application Ser. No. 580,898,

Apr. 26, 1956, now Patent No. 3,168,362, dated Feb. 2,

1965. This application Apr. 6, 1965, Ser. No. 448,559

Claims. (Cl. 62457) This is a continuation of my application Serial No. 170,354, filed February 1, 1962 and now abandoned, which itself is a divisional application of my pending application Serial No. 580,898, entitled, Thermally Insulated Bulk Storage Container, filed April 26, 1956, and issued February 2, 1965 as USP 3,168,362.

This invention relates to an improved container for the storing and conveying of perishable commodities, and more particularly concerns a portable container for the conservation of products which must be held at low temperatures for substantial periods of time.

In the past, several difiiculties have been encountered in the conservation and conveyance of low temperature products, for example, perishable commodities such as whole blood, pharmaceuticals, enzymes, semen, living tissues, or other biological specimens, which must be held at low temperatures for sustained periods of time.

One of the important difficulties concerns the provision of a light-weight, portable storage container capable of being easily handled for shipment by modern transportation, including automotive passenger car. Another problem is the provision of a compact transporting container for maintaining the stored product for a considerable length of time at the low temperature necessary to avoid spoilage.

Still another problem involves the provision of a portable container having a relatively large opening to adapt it for use in the conveyance of packaged liquid products, as Well as solid products of various shapes and sizes, which cannot be simply introduced and withdrawn as can a freefiowing fluid.

Such problems are very difficult to solve in portabletype containers, primarily because the heat leak problem is exceptionally critical in small vessels. The ratio of surface area to storage volume in small containers is very large compared to the large stationary-type, conventional storage containers. In addition, the efficient utilization of space for product storage places a severe limit on the volume available for the refrigerant.

In the present process for storing and shipping perishable commodities in small quantities, such as bull semen for the artificial insemination of cattle, the semen is shipped in amples refrigerated by direct immersion in Water and ice. The difiiculty with using solid refrigerant is that it restricts the mobility of any mechanical equipment or parts that might be used inside the container. Furthermore, much of the stored semen may be wasted by spoilage due to the short term virility of semen at such relatively warm temperatures.

If the semen material could be stored in frozen condition, and transported in portable containers at very low temperatures, such as liquid air or liquid nitrogen temperatures, the material would retain its potency indefinitely, and there would be little or no wastage. The prime advantage of such a system is, of course, that close scheduling of individual semen ampule shipments will no longer be required. Another advantage is that a full and complete selection of different breeds and strains may be made available at all times, independently of the time the semina of such breeds and strains were collected.

In order that such a refrigerated container have the requisite portability, and still operate with maximum effiree ciency and economy, it is necessary that certain inherent problems in design and construction be overcome.

To illustrate by way of example the difficulties that are inherent in the provision of a portable low temperature container, suppose for example that it is desired to store several hundred ampules of semen specimens by immersing them in a bath of liquid nitrogen. Assuming that the contents must be stored in a double-Walled container at liquid nitrogen temperature (320 F.) for about four weeks Without an excessive volume of refrigerant, and Without replenishment of refrigerant, this will require the provision of a highly efiicient insulation such as, for example, a high vacuum polished metal surface system, or a suitable insulating material in vacuum system. This will means that a major path of heat transmission into the container will be through the neck tube of the container and other supporting members. Assume further that the height of the container does not exceed 22 inches, in order that the container may fit in the rear trunk compartment of an automobile.

To more fully appreciate the problems involved in fulfilling the above conditions, it should be pointed out that using a conventional small diameter, thin-walled neck tube to support the inner container inside the outer shell, the contribution of the neck tube to the overall heat transmission will be of such magnitude that attainment of a four week refrigerant holding time without replenishment of refrigerant will be for all intents and purposes, impossible to achieve. Obviously for large neck tube openings, even greater heat leaks will be experienced, since a significant portion of an otherwise well insulated area is thus replaced by an uninsulated opening. As a consequence, refrigeration losses by all modes of heat transfer will be considerably greater.

It is, therefore, an important object of the present invention to provide an improved portable container having a sufiiciently low rate of heat transfer to enable perishable products such as semen and the like to be stored in the refrigerated state at lower temperatures and for longer periods of time than has heretofore been possible.

Another object of the present invention is to provide in a low temperature storage container, a low thermally conductive opening for affording easy access into the container for storing unitized or bulky solids, as well as liquids, at low boiling liquefied gas temperatures for sustained periods of time.

Still another object of the present invention is to provide in a low temperature storage container employing as a refrigerant a low boiling liquefied gas, an improved neck tube construction in combination with a close fitting neck tube plug for utilizing the sensible refrigeration in the escaping refrigerant vapors to reduce the net flow of conductive heat along said tube.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of certain preferred embodiments thereof, taken in conjunction with the acompanying drawings in which:

FIG. 1 is a view in vertical cross-section of an improved container embodying the principles of the present inven tion, also shown is a means for holding units of low-temperature products within the container storage area;

FIG. 2 is a plan view of the container shown in FIG. 1 with a portion broken away to show underlying parts;

FIG. 3 is a sectional view of the container neck plug taken along line 3-3 in FIG. 1;

FIG. 4 is a sectional view of one of the handles of the container taken along line 44 in FIG. 2;

FIG. 5 is a fragmentary sectional view of one of the handles taken along line S-5 in FIG. 2;

FIG. 6 is a fragmentary sectional view of the lower 3, half of the inner container, showing a modification of a basket positioning means;

FIG. 7 is a detail plan view of the modified positioning means taken along the line 77 of FIG. 6.

Briefly stated, the apparatus contemplated by the present invention and hereinafter described, comprises a thermally insulated double-wall container for holding a supply of a vaporizable refrigerant in association with low-temperature-perisha'ble products. Said container comprises essentially an inner vessel having side walls which define the storage compartment for holding said products, a shell surrounding the vessel and spaced slightly outwardly thereof forms an evacuable insulation jacket. A thin walled, elongated neck tube transversing the container upper wall affords access to the storage compartment, said neck tube having an opening or passage extending therethrough substantially less in cross-sectional area than the area of said compartment, thereby minimizing the amount of heat which will be in-leaked to the container refrigerated portion. A low-thermally-conductive plug is constructed and arranged to be supportably received in the neck tube to define a slight annular passage between the adjacently disposed neck tube and plug walls. Refrigerant vapors forming within the container may then pass upwardly along said thin annular passage to the atmosphere and thus reduce the net flow of conductive heat through the neck tube opening, and prevent the formation of excessive gas pressures in the storage compartment.

Double-walled container In FIG. 1 is shown a liquefied gas holding container or double-walled liquid cylinder 10 embodying the principles of the present invention. The double-walled container comprises an inner vessel 11 made from an impervious metal such as stainless steel. This metal is found to resist embrittlement at the low refrigerant temperatures normally encountered when the refrigerant L is such as liquid nitrogen. The inner vessel is generally cylindrically shaped, having at its lower end a dished bottom wall 12, and at its upper end an annular shoulder portion 13, which terminates in an elongated, tubular supporting neck 14. A splash plate 15 may be welded to the inner wall near the top of the vessel 11. The inner vessel 11 is surrounded by a gas-tight shell or jacket 17 of suitable metallic material, which completely encompasses the inner vessel to provide an intervening evacuable insulating space 18 which functions to afford substantial resistance to heat leakage therethrough.

The outer shell 17 includes a shoulder portion 19, and a tapering neck portion 20 which supports the inner vessel 11 at the upper end of its neck 14 by an annular sealing weld joint 21, said joint constituting the lip of the container 10.

For ease of portability and transportation, it is desirable to restrict the weight of the container, and to dimension the container so that it can be carried in the trunk of a car. I have found that in a liter container, an inner and outer vessel diameter of 14 inches and 18 inches, respectively, and an overall container height of 22 inches are most satisfactory. For a larger portable container where manual handling is not essential, i.e. having avolume on the order of about 640 liters, an inner and outer vessel diameter of 42 inches and 48 inches, respectively, and an overall container height of 46 inches have been found to be suitable.

It is to be understood, however, that the invention is not limited to the above dimensions, and that the specific dimensions employed are determined 'by the conditions to which the container is to be subjected.

Any suitable means for stabilizing and centering the inner vessel 11 in the jacket 17 may be used, an example of a preferred embodiment being illustrated in FIG, 1. The inner vessel 11 is centered and held against side sway at its lower end by means of radial rods or spokes 22, made of high tensile strength, low-heat-conductive material such as stainless steel. Each spoke is provided with a hooked outer end 24 adapted to fit into an apertured lug 25 which may be welded to the inside wall of the shell 17 A screw nipple 26 serves to join the inner end of each spoke 22 to a metal ring 27. The latter is welded to the bottom of the inner vessel 11, and provides means for adjusting the tension in each spoke to properly space one vessel within the other.

A metallic cup-shaped cap 31 is pivotally secured to the shoulder 19 by a hinge connection 32, see FIG. 2,- so that the cap may be swung into closed position over the lip 21, and in engagement with the shoulder 19 in the manner indicated in FIG. 1.

The intervening space 18 may be filled with a lowconductive-thermal insulation, such as highly efficient vacuum-polished-nietal surface and or a suitable powder insulating material, 33. For insulation filling purposes, the shoulder 19 may be provided with an opening 34, see FIG. 5, for the reception of a short base fill tube or nipple 35, which may be capped by a metal plug 36, made of 'brass or the like.

To reduce heat leak from the outside to the body of the liquid refrigerant in the vessel 11, the shoulder 19 is provided with an opening 3 8 see FIG. 4, for receiving a nipple 39 having a metal evacuation tube 40 through which the insulation space defined by the container Walls may be exhausted. Depending upon the type of insulation that is employed, and the degree of insulation desired, the pressure within the insulation space should be reduced to a value below 300 microns Hg, and preferably below 100 microns Hg. After exhaustion, the tube 40 is suitable crimped and soldered or welded to effectively seal the vacuous space 18. A filter 41 securely placed over the opening 38, prevents the migration of insulation pow der during evacuation.

As shown in FIG. 1, the absolute pressure within the intervening space 18 may be further reduced and main tained at a low value by attaching an adsorbent container or blister 42 to the lower wall 12 of the inner vessel 11.- The "blister may contain an adsorbent material 43, for example, a zeolitic molecular sieve, either natural or synthetic such as disclosed in United States Patent No. 2,883,243. A filter or screen 44 provided in the blister ensures the retention of the adsorbent in the event the insulation powder is removed, it also prevents migration of the powder into the adsorbent blister.

Referring particularly to FIGS. 4 and 5, protection of the projecting insulation fill tube and the evacuation tube from damaging blows or tampering is provided by handles 45, which completely conceal the tubes from view, and thereby provide the container with a neat appearance. Each handle 45 comprises a pair of spaced, upwardly extending tubular arms 46, 47 which are welded at the lower end to the shoulder 19. Each arm is provided at its upper end with suitable registering openings. for receiving a horizontal bail member 48. A cap 49?,

seals each of the arms 46, 47 from the entry of dust or other matter.. The arm 46 is divided into two tubes, 46a and 46b, provided with complementarily threaded ends. The end portion of tube 46a is undercut to receive the lower threaded end of tube 46!), so that in assembly the outer surfaces of tube 46a and 46b are flush mounted with respect to each other. The joints of the handle 45 with the arms 46, 47 may be secured as by silver brazing to hold the handle parts in assembled position. The handle may thus be assembled without applying heat near the vacuum-tight sealed joints of tubes 35 and 40. 1

Neck tube As a feature of the inventiomthe neck tube 14 of the container is constructed in certain critical proportions to aisoaeei modity, yet presenting a small enough heat-conductive path to obstruct the flow of heat. It should support the weight of the inner container and contents, and yet be thin enough to provide a heat path of exceptionally small cross-sectional area. It should also be long enough to provide a lengthened heat path, While at the same time restricting the overall height of the container so that the latter may fit inside the trunk of a car, It should be strong enough to resist stresses and strains in all positions including side position.

Obviously, optimum neck tube dimensions must consider all the above-mentioned factors. Considering for example the previously-mentioned 25 liter container, a 6 inch long neck tube made from a metal possessing high strength and relatively low conductivity such as Hastalloy steel, and having a diameter of 3 inches and a wall thickness of 0.010 inch, would be admirably suited to fulfill the above needs. For a larger container having a 640 liter capacity, a 12 inch neck tube having a diameter of 15 inches and a wall thicknes of 0.010 inch would be satisfactory.

Referring to FIGS. 1 and 3, a thin-walled plastic dummy stopper or neck plug 28, filled with a low heat conductive medium such as a powder, fits loosely inside the neck tube 14. The adjacent walls of said neck tube and plug define an annular channel or clearance 140. This clearance is sufiicientl-y wide to permit passage of refrigerant vapors upwardly therethrough, and yet suffieiently restricted in opening that the said vapors will sweep both of said walls as they flow upwardly. The plug 28 is provided as shown, with an elongated cylindrical body having an outer surface disposed contiguous with, but spaced slightly from the neck tube wall. The cylindrical body is provided at its upper end with a flange 29 having a diameter slightly greater than the neck tube diameter to supportingly hold the plug in position within the neck tube.

When, as shown in FIG. 1, the product holding means are supported in the refrigerating compartment by elongated handles 58 extending to the neck tube upper lip, these handles are positioned adjacent the neck tube wall. To accommodate said handles, longitudinal grooves 30 may be formed about the circumference of the plug 28. These grooves are peripherally evenly spaced and small enough to define with the handle a slight passage for refrigerant vapors. Also, when this type of handle is employed, the plug flange 29 will rest on the upper or bent portion 60 of the handle 53 affording a circumferential vent opening for vapors. When, of course, the product holding mean-s are not supported on the neck tube upper lip, the flange 29 may be adapted to be paced from the neck tube to provide the necessary peripheral venting passage at the plug upper end.

The provision of the neck plug 28 to occupy the majority of the free space in the neck tube 14 is both desirable and necessary for obtaining maximum advantage in the present invention. The primary function of the plug 28, as mentioned, is to cause the refrigerant vapor, which is evolved due to unavoidable heat leak, to channel or flow upwardly close to, and in contact with the metal surface of the neck tube 14 and the handles 58 when this type of handle is employed. The vapor thereby absorbs any heat which otherwise would be conducted down the neck tube 14 and handles 58, and in so doing is itself warmed to essentially atmospheric temperature. In this manner, the sensible refrigeration in the refrigerant vapor is recovered and the net heat conducting characteristic of the neck tube is effectively reduced. This permits the use of a large diameter access tube 14 without incurring serious heat losses, and thus results in minimum refrigerant consumption while still permitting a greater portion of the container storage volume to be utilized.

Product holding means In order to more efficiently utilize the container storage capacity, different embodiments of product holding means may be employed. One such means is shown in the fig ures, and has been previously mentioned in relation to the neck tube 14 and plug 28 arrangement, a fuller description of this holder follows. As shown in FIG. 1, there is provided a number of product holder units or ampuleholding baskets 50. In this device, all the parts of the basket are immersed in, and are in direct contact with the liquid refrigerant L. Each of the baskets comprises primarily means for suspending the product holding ampules in such a manner as to fit the maximum number of ampule into a particular storage compartment.

The product holding means is positioned in said compartment by the elongated handle 58 having the formed upper end 60 to supportingly engage the container. As shown in FIG. 6, the handle arrangement is such that when in the supported position, the perishable products will be disposed outwardly and toward the compartment walls. Keeping said product holders away from the neck tube, permits any of said devices to be inserted or removed without disturbing those already positioned.

For example, when assembled within the container 11, the baskets 50 are preferably stored in the large diameter portion of the container about a center space disposed directly below the opening in the neck tube 14. Referring to FIG. 2, for the most elfective utilization of available storage space, six maximum sized baskets having a diameter slightly smaller than the neck tube diameter may be held. These baskets are circularly arranged in the large diameter portion of the container about the center portion. A larger or smaller number may of course be provided if so desired. For this purpose, and referring to FIGS. 1, 6 and 7, the bottom wall 12 of the inner container 11 is provided with an annular supporting platform or pedestal 70, 70', which is securely attached to said bottom wall. The outer ring of each of the surrounding baskets 50 extends slightly below the upper surface of the pedestal 70, being supportingly held at this level by the engagement of the radially outwardly pointing hooked end of the handle 58 with the .lip 21. As a result, the ring 55 is in proximity with the side surface 71 of the pedestal 70, thereby limiting the extent to which the basket 50 may sway.

From the above description, it will be seen that the present invention provides an improved portable container having a sufficiently low rate of heat transfer to enable perishable commodities such as bull semen to be stored in the refrigerated state for longer periods of time than has heretofore been possible. Using as a refrigerant a low boiling liquefied gas, such as liquid nitrogen, a perishable product may be stored indefinitely, and refrigeration need not be replenished frequently. The improved neck tube access opening automatically relieves gas pressure in the container, and simultaneously reduces the net flow of conductive heat downwardly along the tube, thereby permitting the use of a large diameter neck tube in comparison to the storage volume of the container.

From the foregoing description it may be seen that the disclosed invention provides a highly improved, although simple apparatus for storing perishable materials over relatively long periods of time. It is understood however, that certain changes and modifications may be made in the present embodiment without departing from the spirit and scope of the invention.

What is claimed is:

1. An insulation jacketed container for storing perishable products at a low temperature, said container having a storage chamber for holding said products in contact with a vaporizable liquid refrigerant, a low thermally conductive neck tube member transversing a wall of the container and having a straight smooth inner wall to define an elongated passage in communication with the storage chamber affording access thereto, a low thermally conductive plastic plug slideably supported ,in the neck tube substantially occupying said longitudinal passage, said plug being constructed and arranged with a straight smooth outer surface to provide a narrow unobstructed annular channel between the neck tube inner wall and the plug outer surface to cause vapors of the vaporizable refrigerant to flow in heat exchange relation along the wall of said neck tube passage for utilizing the sensible refrigeration in the refrigerant vapors to reduce the net flow of conductive heat through said opening and to automatically prevent the formation of excessive gas pressure in said vessel as a result of heat leakage, whereby said vessel may store said perishable products for sustained periods of time.

2. A container for storing refrigerated products at a low temperature, said container having a storage chamber for holding said products in contact with a vaporizable liquid refrigerant, a low thermally conductive neck tube member transversing an upper Wall of the container and having a straight smooth inner wall to define an elongated cylindrical passage in communication with the storage chamber and affording access thereto, a low thermally conductive plastic plug supportably positioned in the neck tube, said plug having an elongated body disposed to substantially occupy said cylindrical passage but loosely disposed therein with a straight smooth outer surface to define a slight unobstructed annular channel between the adjacent neck tube Wall and the body outer surface, whereby vapors from said refrigerant may flow upwardly through said annular channel in heat exchange contact with the neck tube wall and be thence vented to the atmosphere.

3. A container substantially as described in claim 2, wherein the annular channel defined by the neck tube wall and the low thermally conductive plastic plug outer surface is approximately of an inch in width.

4. A low temperature container for holding a supply of perishable products and a low temperature vaporizable refrigerant gas, said container comprising: a vessel having a storage compartment for holding a supply of the vaporizable gas, a shell surrounding said vessel and spaced outwardly therefrom to define an insulation space therebetween, a low thermally conductive neck tube member transversing said insulation space and joined to the vessel and shell respectively, said member having a straight smooth inner wall defining an elongated opening in communication with the storage chamber affording access thereto, a low thermally conductive plastic plug supportably positioned in the neck tube to'substantially occupy said opening, said plug being constructed and arranged with a straight smooth outer surface to provide a narrow unobstructed annular channel between the neck tube inner wall and the plug outer surface to cause vapors of the vaporizable refrigerant to flow in heat exchange relation along the wall of said neck tube opening and said plug for utilizing the sensible refrigeration in the refrigerant vapors to reduce the net flow of conductive heat through said opening, and to prevent the formation of excessive gas pressure in said vessel as a result of heat leakage, whereby said vessel may store said perishable products for sustained periods of time.

5. A low temperature container for holding a supply of perishable products and a low temperature vaporizable refrigerant gas, said container comprising: a vessel having a storage compartment for holding a supply of the vaporizable gas, a shell surrounding said vessel and spaced outwardly therefrom to define an insulation space therebetween, a low thermally conductive neck tube member transversing an upper Wall of the vessel and shell having a straight smooth inner wall to define an elongated cylindrical passage in communication with the storage chamber atfording access thereto, a low thermally conductive plastic plug supportably held in the neck tube, said plug having an elongated body of cylindrical crosssection substantially occupying said cylindrical passage but loosely positioned therein with a smooth outer surface to define a slight unobstructed annular channel therebetween, whereby vapors from said refrigerant gas may flow upwardly through said channel in contact with the adjacently disposed plug body and the neck tube wall and be thence vented to the atmosphere.

6. A low temperature container substantially as described in claim 5 wherein the annular channel defined by the neck tube wall and the low thermally conductive plastic plug is approximately 3 of an inch in width.

7. In a low temperature container for storing a supply of perishable products and a low temperature vaporizable liquid refrigerant comprising: a thin walled vessel defining a storage compartment having an upper wall and a generally circular cross-sectional area for holding a supply of the vaporizable gas and the perishable products, a shell surrounding said vessel and disposed outwardly therefrom to define an insulating space, the combination therewith of a'low thermally conductive neck tube transversing said insulating space at the container upper wall, said neck tube having opposed ends connected to the vessel and shell respectively and being communicated by :a cylindrical passage having a straight smooth wall, a low thermally conductive plastic plug supportably received in the neck tube, said plug having an elongated body with a straight smooth outer surface disposed contiguous with but spaced slightly from the cylindrical passage straight smooth wall defining an unobstructed annular channel, a flange extending outwardly from the body upper portion and support-ably held at the neck tube upper end affording venting means for refrigerant vapor, whereby said vapors may pass along said annular channel in contact with the neck tube wall and thence be vented to the atmosphere.

8. In a low temperature container for storing a supply of perishable products and a low temperature vaporizable refrigerant liquid comprising: a thin walled vessel defining a storage compartment having an upper wall and a generally circular cross-sectional area for holding a supply of the vaporizable refrigerant gas and the perishable products, a thin shell surrounding said vessel and disposed outwardly thereof to define an evacuable insulating space, the combination therewith of a low thermally conductive metallic neck tube member transversing said insulating space at the container upper wall, said member having opposed ends sealably joined to the vessel and shell respectively, said ends being connected by a cylindrical passage formed by a straight smooth inner wall affording access to the storage area, said passage being substantially smaller in cross-sectional area than the storage space cross-sectional area and disposed centrally of said storage area, a low thermally conductive plastic plug supportably positioned in the neck tube to substantially occupy said cylindrical passage, said plug constructed and arranged with a cylindrical outer surface to provide a narrow unobstructed annular channel between the neck tube inner wall and the plug outer surface to cause vapors of the vaporizable refrigerant to flow in heat exchange relation along the wall of said neck tube passage and said plug for utilizing the sensible refrigeration in the refrigerant vapors to reduce the net flow of conductive heat along said wall and into the storage area.

9. For use in a refrigeration apparatus having a storage compartment holding a quantity of a vaporizable refrigerant, and having means forming an elongated access passage with a smooth straight wall in communication with said storage compartment; a low thermally conductive plug having an outer end and an opposite inner end removably received in said access passage comprising: an elongated low conductive plastic body means having an insulation compartment and extending substantially the length of said access passage, theouter surface of said body being smooth, straight and disposed contiguous with but spaced slightly from the walls of said access passage to form an unobstructed annular channel, and plug positioning means appended to the outer end of said body and being supportably held by said passage forming means.

10. For use in a refrigeration apparatus having a storage compartment holding a quantity of a vaporizable refrigerant, and having an upright cylindrical tubular member forming an elongated access passage having a straight smooth wall in communication with said storage compartment; a low thermally conductive plastic plug depending from the upper edge of said tubular member to occupy substantially all of said passage, said plug comprising: an elongated plastic body of cylindrical crosssection having a straight smooth outer surface defining an inner compartment, an insulating medium held in said compartment, the outer cylindrical surface of said body extending substantially the length of said passage and being spaced slightly from the access passage Wall to define an unobstructed annular channel, and a flange extending outwardly from the body to supportedly engage the said tubular member upper edge.

References Cited by the Examiner EDWARD J. MICHAEL, Primary Examiner. 

1. AN INSULATION JACKETED CONTAINER FOR STORING PERISHABLE PRODUCTS AT A LOW TEMPERATURE, SAID CONTAINER HAVING A STORAGE CHAMBER FOR HOLDING SAID PRODUCTS IN CONTACT WITH A VAPORIZABLE LIQUID REFRIGERANT, A LOW THERMALLY CONDUCTIVE NECK TUBE MEMBER TRANSVERSING A WALL OF THE CONTAINER AND HAVING A STRAIGHT SMOOTH INNER WALL TO DEFINE AN ELONGATED PASSAGE IN COMMUNICATION WITH THE STORAGE CHAMBER AFFORDING ACCESS THERETO, A LOW THERMALLY CONDUCTIVE PLASTIC PLUG SLIDEABLY SUPPORTED IN THE NECK TUBE SUBSTANTIALLY OCCUPYING SAID LONGITUDINAL PASSAGE, SAID PLUG BEING CONSTRUCTED AND ARRANGED WITH A STRAIGHT SMOOTH OUTER SURFACE TO PROVIDE A NARROW UNOBSTRUCTED ANNULAR CHANNEL BETWEEN THE NECK TUBE INNER WALL AND THE PLUG OUTER SURFACE TO CAUSE VAPORS OF THE VAPORIZABLE REFRIGERANT TO FLOW IN HEAT EXCHANGE RELATION ALONG THE WALL OF SAID NECK TUBE PASSAGE FOR UTILIZING THE SENSIBLE REFRIGERATION IN THE REFRIGERANT VAPORS TO REDUCE THE NET FLOW OF CONDUCTIVE HEAT THROUGH SAID OPENING AND TO AUTOMATICALLY PREVENT THE FORMATION OF EXCESSIVE GAS PRESSURE IN SAID VESSEL AS A RESULT OF HEAT LEAKAGE, WHEREBY SAID VESSEL MAY STORE SAID PERISHABLE PRODUCTS FOR SUSTAINED PERIODS OF TIME. 